netfilter: nft_meta: offload support for interface index

This patch adds support for offloading the NFT_META_IIF selector.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

include/net/netfilter/nf_tables_offload.h

@@ -45,6 +45,7 @@ struct nft_flow_key {
 	struct flow_dissector_key_ip			ip;
 	struct flow_dissector_key_vlan			vlan;
 	struct flow_dissector_key_eth_addrs		eth_addrs;
+	struct flow_dissector_key_meta			meta;
 } __aligned(BITS_PER_LONG / 8); /* Ensure that we can do comparisons as longs. */
 
 struct nft_flow_match {

net/netfilter/nft_meta.c

@@ -547,6 +547,10 @@ static int nft_meta_get_offload(struct nft_offload_ctx *ctx,
 				  sizeof(__u8), reg);
 		nft_offload_set_dependency(ctx, NFT_OFFLOAD_DEP_TRANSPORT);
 		break;
+	case NFT_META_IIF:
+		NFT_OFFLOAD_MATCH(FLOW_DISSECTOR_KEY_META, meta,
+				  ingress_ifindex, sizeof(__u32), reg);
+		break;
 	default:
 		return -EOPNOTSUPP;
 	}